This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The specific aims of the study are 1) To determine the effects of exercise on insulin sensitivity in insulin-resistant African-American and Hispanic adolescents;2) To determine the effects of exercise on fibrinolytic markers in insulin-resistant African-American and Hispanic adolescents. The hypothesis is that insulin-resistant African-American and Hispanic adolescents will show significant improvement of insulin sensitivity (SI) and positive changes associated with fibrinolytic markers and lipid profile after a 1 month pre-training period and two-months of supervised, moderate intensity aerobic exercise. Part I. Insulin-resistant African American and Hispanic adolescents from the DC metro area will be recruited through various recruitment efforts. Potential participants will have 2 screening visits in which their medical history, physical activity level, body mass index, and fasting plasma glucose and insulin or OGTT results will determine eligibility. Part 2. If inclusion criteria is met, the subjects will undergo a 2 week dietary stabilization period, treadmill exercise testing, IVGTT, blood draws for fibrinolytic and lipid markers, DEXA scan, and anthropometric measurements. Subjects will have a 1 month pre-training period and 2 months of supervised, moderate intensity aerobic exercise. All baseline testing will be repeated after the exercise period to see any significant differences.